Method for detecting fault of power system and related

Abstract

The invention provides a method for detecting a fault of a power system and related equipment. The method comprises the following steps: calculating the amplitude difference of positive-sequence current, the amplitude difference of negative-sequence current, the amplitude difference of zero-sequence current and the amplitude difference of zero-sequence voltage of a three-phase node of secondary equipment according to a current instantaneous value and a voltage instantaneous value of the three-phase node of the primary equipment; based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current, determining whether the power system has a disconnection fault; and when the disconnection fault cannot be determined through the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current, determining whether the disconnection fault occurs in the power system according to the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage. The primary and secondary equipment fusion fault detection method can more comprehensively and accurately analyze whether the power system has a fault or not.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a method for detecting faults in power systems and related equipment. Background Art

[0002] As an important part of the power system, the safe and reliable operation of the medium voltage distribution network is of great significance to people's normal electricity life. In particular, if the most common single-phase disconnection fault is not discovered in time, it will cause overvoltage, burn the rotating motor, and even cause forest fires and serious accidents such as electric shock to people and animals.

[0003] For broken line grounding faults, there are many related small current grounding fault detection methods due to the large grounding resistance at the fault point and the weak fault current. However, the research on broken line non-grounding fault detection has not received much attention. Summary of the invention

[0004] In view of this, the purpose of the present application is to propose a method for detecting faults in an electric power system and related equipment to solve or partially solve the above-mentioned problems.

[0005] Based on the above purpose, the present application provides a method for detecting a fault in an electric power system, comprising: Obtaining instantaneous current values ​​and instantaneous voltage values ​​of three-phase nodes of a primary device in the power system; Calculate the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node of the secondary device according to the instantaneous value of the current and the instantaneous value of the voltage; Determining whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current; In response to failure to determine a line break fault through the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current, determining whether a line break fault occurs in the power system based on the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage.

[0006] Optionally, the calculating, according to the instantaneous current value and the instantaneous voltage value, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage of the three-phase node further comprises: Calculating the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; According to the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage at an interval of one power frequency cycle are calculated.

[0007] Optionally, the determining whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current further comprises: In response to the amplitude difference of the positive sequence current being less than zero, the amplitude difference of the negative sequence current being greater than zero, and the sum of the amplitude differences of the plurality of positive sequence currents being greater than or equal to a first threshold, it is determined that a line break fault occurs in the power system.

[0008] Optionally, determining whether a line break fault occurs in the power system according to the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage further includes: In response to the amplitude difference of the zero-sequence current being greater than zero, the amplitude difference of the zero-sequence voltage being greater than zero, and the amplitude difference of the zero-sequence voltage being greater than or equal to a second threshold, it is determined that a line break fault occurs in the power system.

[0009] Optionally, the determining whether a line break fault occurs in the power system further comprises: in response to a line break fault occurring in the power system, determining a location where the line break fault occurs in the power system.

[0010] Optionally, in response to a line break fault occurring in the power system, determining a location where the line break fault occurs in the power system further comprises: In response to a line disconnection fault occurring in the power system, calculating a line voltage amplitude difference between any two phase nodes in the three-phase nodes; The location where the line disconnection fault occurs in the power system is determined according to the line voltage amplitude difference.

[0011] Optionally, determining the location where the power system has a line break fault according to the line voltage amplitude difference further comprises: In response to the line voltage amplitude difference being less than or equal to a third threshold, it is determined that a location where a line break fault occurs in the power system is on a power source side of the power system.

[0012] Based on the above purpose, the present application also provides a device for detecting a fault in an electric power system, comprising: An acquisition module is configured to acquire instantaneous current values ​​and instantaneous voltage values ​​of three-phase nodes in the power system; A calculation module, configured to calculate the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; A first detection module is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current; The second detection module is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage in response to the inability to determine a line break fault through the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current.

[0013] Optionally, the computing module is further configured to: Calculating the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; According to the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage at an interval of one power frequency cycle are calculated.

[0014] Optionally, the first detection module is further configured to: In response to the amplitude difference of the positive sequence current being less than zero, the amplitude difference of the negative sequence current being greater than zero, and the sum of the amplitude differences of the plurality of positive sequence currents being greater than or equal to a first threshold, it is determined that a line break fault occurs in the power system.

[0015] Optionally, the second detection module is further configured to: In response to the amplitude difference of the zero-sequence current being greater than zero, the amplitude difference of the zero-sequence voltage being greater than zero, and the amplitude difference of the zero-sequence voltage being greater than or equal to a second threshold, it is determined that a line break fault occurs in the power system.

[0016] Optionally, the second detection module is further configured to: In response to a line break fault occurring in the power system, a location where the line break fault occurs in the power system is determined.

[0017] Optionally, the second detection module is further configured to: In response to a line disconnection fault occurring in the power system, calculating a line voltage amplitude difference between any two phase nodes in the three-phase nodes; The location where the line disconnection fault occurs in the power system is determined according to the line voltage amplitude difference.

[0018] Optionally, the second detection module is further configured to: In response to the line voltage amplitude difference being less than or equal to a third threshold, it is determined that a location where a line break fault occurs in the power system is on a power source side of the power system.

[0019] Based on the above purpose, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method described in any of the above embodiments is implemented.

[0020] Based on the above purpose, the present application also provides a non-transitory computer-readable storage medium, which stores computer instructions, and the computer instructions are used to enable a computer to execute the method described in any of the above embodiments.

[0021] From the above, it can be seen that the present application provides a method and related equipment for detecting faults in an electric power system. The method includes: calculating the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage of the three-phase nodes of the secondary equipment according to the instantaneous current and voltage of the three-phase nodes of the primary equipment; determining whether a line break fault occurs in the electric power system based on the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current; when the line break fault cannot be determined by the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current, determining whether a line break fault occurs in the electric power system based on the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage. The fault detection method of the present application that integrates primary and secondary equipment can more comprehensively and accurately analyze whether a fault occurs in the electric power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 The equivalent circuit of a single-phase line break fault in a system with non-effectively grounded neutral point is shown.

[0024] Figure 2 A flowchart of an exemplary method for detecting a fault in an electric power system according to an embodiment of the present application is shown.

[0025] Figure 3 A schematic diagram of an exemplary device for detecting a fault in an electric power system according to an embodiment of the present application is shown.

[0026] Figure 4 A schematic diagram of an exemplary electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0028] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0029] As an important part of the power system, the safe and reliable operation of the medium-voltage distribution network is of great significance to people's normal electricity life. With the continuous expansion of the scale of the current medium-voltage distribution network, the operating environment has become more and more complex. The continuous improvement of the circuit insulation rate has led to low line heat dissipation efficiency, and the line is prone to melting due to high temperature. In addition, due to the influence of extreme weather such as lightning strikes, line breakage failures occur frequently. In particular, if the most common single-phase line breakage failure among line breakage failures is not discovered in time, overvoltage will be generated, rotating motors will be burned, and even serious accidents such as forest fires and electric shocks to people and animals will be caused. For line break grounding faults, there are many related small current grounding fault detection methods due to the large grounding resistance of the fault point and the weak fault current. However, the research on line break and ungrounded fault detection has not received much attention. Therefore, the method and related equipment for detecting faults in the power system provided in the present application are of great significance to the security of the power system.

[0030] A method for detecting faults in an electric power system provided in the present application can be applied to fault detection in an electric power system. The method combines the monitoring information of primary equipment and secondary equipment to judge and detect faults. Primary equipment refers to equipment directly involved in power transmission and distribution, such as transmission lines, transformers, busbars, etc.; secondary equipment refers to equipment used to monitor and control primary equipment, such as relay protection devices, measuring instruments, etc.; primary and secondary fusion combines the real-time operating data of primary equipment with the protection and measurement information of secondary equipment to achieve more comprehensive and accurate fault analysis and judgment. A method for detecting faults in an electric power system provided in the present application is an algorithm implemented on a feeder terminal unit (FTU).

[0031] In the related art, the methods for identifying and locating single-phase line break faults in medium-voltage distribution networks include line selection methods based on negative-sequence current characteristics and phase current characteristics. However, these methods mainly rely on current-related characteristics, so they lack sensitivity or even fail when the power grid is lightly loaded or unloaded, and there are large errors in the measurement of negative-sequence components. In addition, they are also susceptible to grid imbalance and lateral faults. The methods in the related art also include line selection methods based on zero-sequence voltage amplitude difference. However, this method relies on communication and data synchronization between FTUs at different locations, usually requires more detection equipment and complex communication systems, high cost, complex implementation principles, and methods that rely on current-related characteristics, lack sensitivity or even fail when the power grid is lightly loaded or unloaded, and there are large errors in the measurement of negative-sequence components, and the recognition accuracy is not high.

[0032] For the feeder terminal unit (FTU) line break protection strategy in the local feeder automation system, it is necessary not only to achieve accurate and rapid line break fault detection, but also to determine whether the line break fault point is located upstream (power supply side) or downstream (load side) of the FTU. Therefore, the method provided in this application comprehensively analyzes the characteristics of voltage, current and each sequence component of the typical line break pattern in the medium-voltage distribution network, aiming to propose a fault detection algorithm that integrates the changes in zero-sequence components, phase current phase and line voltage amplitude. By comprehensively comparing the changes in the zero-sequence voltage amplitude, phase current phase and line voltage amplitude of the fault point, the FTU can accurately determine the occurrence and location of the single-phase ungrounded line break fault, thereby filling the shortcomings of the existing fault detection algorithm.

[0033] In order to solve the problem of lack of effective detection and protection algorithms for accurate identification and determination of single-phase line break faults, the method provided in this application studies the change characteristics of the three-phase current phase difference, zero-sequence voltage component and line voltage amplitude signal in the circuit when a single-phase line break fault occurs based on a composite sequence network. The fault type is indexed according to the easy-to-observe characteristic of the zero-sequence voltage and current amplitude jump of the fault phase, and the occurrence of a line break fault is identified according to whether the phase of the phase current crosses the zero point abruptly. Finally, the fault location is determined according to the different characteristics of the line voltage amplitude at different positions of the fault line. Through simulation and actual measurements, the test results show that the fault detection algorithm that integrates the changes in zero-sequence current voltage, phase current and line voltage amplitude can successfully locate the fault, laying the foundation for the subsequent design of a line break fault detection scheme with better performance.

[0034] Figure 1 The equivalent circuit of a single-phase line break fault in a system with non-effectively grounded neutral point is shown.

[0035] Assuming the line A single-phase disconnection fault occurs in the phase. , , They are the three-phase (A phase, B phase and C phase) power supply of the system; N is the neutral point on the power supply side at the disconnection position; M is the neutral point on the load side at the disconnection position; is the total equivalent capacitance to ground of all non-fault lines; is the capacitance of the fault line to ground; γ represents the coefficient, ranging from 0 to 1; , , The three-phase voltage of the medium voltage line on the power supply side at the disconnection location; , , is the three-phase voltage on the load side of the disconnection position; , are the grounding transition resistances of the disconnected wires on both sides of the disconnection point, , The values ​​of are the same, By setting , The different combinations of the two types of grounding can include grounding on the load side of the line, grounding on the power supply side of the line, and grounding on both sides of the line. , When it approaches positive infinity, it means that the corresponding side has a disconnected line and ungrounded fault; is the load equivalent impedance of the normal line; Z is the load equivalent impedance downstream of the fault line disconnection point. The line impedance is much smaller than the line-to-ground capacitance and load impedance and can be ignored.

[0036] When a single-phase line break occurs, the values ​​of the sequence current before and after the line break will change. This change can be used as a starting criterion for whether a line break occurs. is the instantaneous value of phase A current before the fault, (i is p, n, 0 respectively) represent the positive (p), negative (n), and zero (0) sequence impedances of the fault point, respectively. , , They are respectively the instantaneous value of positive sequence current, the instantaneous value of negative sequence current and the instantaneous value of zero sequence current. After a one-way line break fault occurs, since the low-voltage side of the main transformer of the distribution network and the high-voltage side of the load transformer are both connected in a triangle, the impedance in the zero-sequence network can be approximated to be infinite. The simplified expression formula of the positive sequence, negative sequence and zero sequence current generated by this fault is as follows:

[0037] After a line break fault occurs, the positive and negative sequence currents are opposite in direction to the normal currents, and their post-fault change characteristics are more significant, making them easy to distinguish from healthy phase circuits. A specific analysis of the changes in the positive and negative sequence currents before and after the fault shows that the positive and negative sequence current changes in the line after the fault are consistent, while the corresponding BC two-phase currents are opposite in direction to the phase currents before the fault, and the value is 3 / 2 of the latter. Therefore, when making a single-phase circuit breaker fault judgment, it can be based on the positive and negative sequence current change amplitudes.

[0038] based on Figure 1 The equivalent circuit diagram shown can be used to simulate the algorithm. The program is developed based on embedded software and runs in the FTU algorithm board. When the algorithm board is powered on, the line break protection algorithm starts running. Through the hardware circuit, the instantaneous current and voltage values ​​of A, B, and C (for example, three-phase nodes) in the monitoring line are sampled and extracted. The instantaneous current value can include the three-phase current , the instantaneous voltage value can include the three-phase voltage After filtering the sampled original waveform, the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current, and the amplitude difference of the zero sequence voltage are calculated.

[0039] If the line is unloaded or lightly loaded, the current is small, and the start criterion may not be met when a line break occurs. Therefore, an additional criterion can be added to use the change in zero-sequence voltage for auxiliary judgment:

[0040] in, represents the amplitude of zero-sequence current, Represents the amplitude difference of zero-sequence current, represents the amplitude of the zero-sequence voltage, Represents the amplitude difference of zero-sequence voltage, Represents a variable, The number of sampling points of a waveform representing one cycle, , and It represents a fixed constant, which can be taken as 0.01.

[0041] After the start-up criterion is determined, since a small current ground fault will also cause a sudden change in zero-sequence voltage, the phase current zero-crossing phase is required as a criterion to further determine the cause of the fault. In some embodiments, if a single-phase line break occurs in phase A, the current amplitude of phase A drops to 0, and the current amplitudes of phases B and C remain unchanged, but the phases are opposite. Based on this, whether the phases of the currents of phases B and C are in opposite phases can be used to determine whether a line break occurs and in which phase the line break occurs.

[0042]

[0043] in, It represents the instantaneous value of the AB two-phase line voltage. It represents the instantaneous value of the BC two-phase line voltage. It represents the instantaneous value of the CA two-phase line voltage, Indicates the instantaneous value of the neutral point voltage, It means C / C2, C=C1+C2, is the formula after Fourier transformation, C represents the total capacitance of the circuit, Indicates the A phase power supply, Indicates the B phase power supply, Indicates the C phase power supply, represents the equivalent impedance of the fault line, Represents resistance , The value of .

[0044] It can be seen that the line voltage on the disconnected load side is , , The voltages of the neutral point N of the upstream (power supply side) lines and the line voltages remain unchanged before and after the line break; the voltages of the neutral point M of the medium-voltage lines downstream (load side) of the line break and at least one of the three line voltages has an amplitude lower than 0.8Uset (the third threshold value). Therefore, the line break position can be determined by the amplitude change of the line voltage before and after the line break (for example, the line voltage amplitude difference).

[0045] If it is a line break fault, in some embodiments, the fault area can be determined based on the change in the effective value of the line voltage. If the line break fault point is located downstream of the FTU monitoring point, the three-phase voltage at the monitoring point still exists, and only the current of the faulty phase becomes 0, so the line voltage is the same as when there is no fault; if the fault point is located upstream of the FTU monitoring point, the phase voltage and phase current of the faulty phase both become 0, so the line voltage will drop to less than 0.8 times the normal value.

[0046] Specifically, in some embodiments, the effective value of the line voltage may be obtained, and the line voltage amplitude may be calculated by the effective value of the line voltage:

[0047] in, Indicates the line voltage amplitude, Indicates the effective value of line voltage.

[0048] As an optional embodiment, an oscilloscope or other measuring equipment can be used to directly measure the amplitude of the line voltage. .

[0049] By calculating the line voltage amplitude when the power system fails and the line voltage amplitude before the failure, the line voltage amplitude difference can be calculated. In some embodiments, if the line voltage amplitude difference is less than the third threshold, it is determined that the location of the power system disconnection fault is on the power supply side of the power system.

[0050] Figure 2 A flowchart of an exemplary method for detecting a fault in an electric power system according to an embodiment of the present application is shown.

[0051] like Figure 2 As shown in the figure, the program is developed based on embedded software and runs in the FTU algorithm board. When the algorithm board is powered on, the line break protection algorithm starts to run. Through the hardware circuit, the instantaneous values ​​of the three-phase currents of the A, B, and C three-phase nodes in the monitoring line are sampled and extracted. (For example, the instantaneous value of phase A current before the fault , Instantaneous value of phase B current before fault , Instantaneous value of phase C current before fault ), three-phase voltage instantaneous value (For example, the instantaneous value of phase A voltage before the fault , Instantaneous value of phase B voltage before fault , Instantaneous value of phase C voltage before fault ), after filtering the sampled original waveform, the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current, and the amplitude difference of the zero sequence voltage are calculated.

[0052] In some embodiments, according to the symmetrical component method, the positive, negative and zero sequence current amplitudes of phase A can be calculated by the following formula.

[0053]

[0054] in, is the amplitude of the positive sequence current, is the amplitude of the negative sequence current, is the amplitude of the zero-sequence current, is a complex operator, = , represents the imaginary unit, is the instantaneous value of phase A current before the fault, is the instantaneous value of phase B current before the fault, is the instantaneous value of phase C current before the fault.

[0055] The amplitude of the zero-sequence voltage can be calculated using the following formula:

[0056] in, is the instantaneous value of phase A voltage before the fault, is the instantaneous value of phase B voltage before the fault, is the instantaneous value of phase C voltage before the fault, is the amplitude of the zero-sequence voltage.

[0057] According to the sampling frequency, each cycle (periodic waveform) is read N The data of the sampling points can be expressed by the following formulas:

[0058]

[0059] in, , It is the difference in amplitude between the positive sequence current and the negative sequence current at an interval of one power frequency cycle. is the amplitude difference of the zero-sequence current at intervals of one power frequency cycle, is the amplitude difference of the zero-sequence voltage at intervals of one power frequency cycle, is the amplitude of the positive sequence current, is the amplitude of the negative sequence current, is the amplitude of the zero-sequence current, is the amplitude of the zero-sequence voltage.

[0060] Determine the amplitude difference between positive sequence current and negative sequence current, is the amplitude difference of k consecutive positive sequence currents the sum of To set the line Positive sequence current value , set to 0.5 If satisfied <0, >0, and 0.5 (For example, the first threshold), it is determined that a line break fault occurs in the power system. If the condition is not met, the amplitude difference of the zero-sequence current and the zero-sequence voltage is used to assist in the judgment (judging the amplitude difference of the zero-sequence current and the zero-sequence voltage).

[0061]

[0062] When the amplitude difference of the positive and negative sequence currents (i.e. the amplitude change) cannot determine whether a single-phase disconnection fault has occurred, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage are used to assist in the determination. is the zero-sequence overvoltage threshold value, which can be determined by referring to the ordinary zero-sequence overvoltage protection value and comparing the amplitude difference of the zero-sequence voltage Δ When the amplitude difference of zero-sequence voltage is Δ When it is greater than or equal to a given value (second threshold), it is considered that a line fault occurs in the power system. If it is less than the given value, there is no disconnection fault.

[0063]

[0064] When a line break fault occurs in the power system, in some embodiments, the line voltage amplitude difference between any two phase nodes in the three-phase nodes can be calculated, and the location of the line break fault in the power system can be determined based on the line voltage amplitude difference.

[0065] Calculate the phase of the zero-crossing point of the three-phase current. Start from the moment of disconnection to find the zero-crossing point of the three-phase current. Take phase A as an example. When the following formula is satisfied, k is the zero-crossing point. Use the same method to find the zero-crossing point of phases BC.

[0066]

[0067] Determine whether there are two-phase current anti-phase, that is, whether the phase difference is If there is a change in the value of the two-phase current If the two-phase current is detected to be in phase reversal, it is considered that a line break fault has occurred. The line voltage amplitude difference between any two phase nodes in the three-phase node is calculated (for example, ). If there is no two-phase current reversal, it is determined that there is no disconnection fault.

[0068] Specifically, in some embodiments, the effective value of the line voltage may be obtained, and the line voltage amplitude may be calculated by the effective value of the line voltage:

[0069] in, Indicates the line voltage amplitude, Indicates the effective value of line voltage.

[0070] As an optional embodiment, an oscilloscope or other measuring equipment can be used to directly measure the amplitude of the line voltage. .

[0071] By calculating the line voltage amplitude at the time of the power system fault and the line voltage amplitude before the fault, the line voltage amplitude difference can be calculated.

[0072] Calculate the line voltage amplitude difference between any two-phase nodes. After the line break protection is activated, determine whether a line break fault has occurred and the location of the line break fault. If the following formula is satisfied, it is determined that the location of the line break fault in the power system is on the power supply side of the power system (line break on the power supply side). If not, it is determined that a line break has occurred on the load side.

[0073] Any one of (e.g., a third threshold), where Indicates the rated line voltage.

[0074] Report the fault information and the algorithm ends.

[0075] The present application provides a method and related equipment for detecting faults in an electric power system. The method includes: calculating the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage of the three-phase nodes of the secondary equipment according to the instantaneous current and voltage of the three-phase nodes of the primary equipment; determining whether a line break fault occurs in the electric power system based on the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current; when the line break fault cannot be determined by the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current, determining whether a line break fault occurs in the electric power system based on the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage. The fault detection method of the present application integrating primary and secondary equipment can more comprehensively and accurately analyze whether a fault occurs in the electric power system.

[0076] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or server. The method of this embodiment can also be applied to a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the described method.

[0077] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0078] Based on the same technical concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a device for detecting faults in an electric power system.

[0079] refer to Figure 3 , the device for detecting a fault in an electric power system comprises: The acquisition module 301 is configured to acquire instantaneous current values ​​and instantaneous voltage values ​​of three-phase nodes of a primary device in the power system.

[0080] The calculation module 302 is configured to calculate the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node of the secondary device according to the instantaneous current value and the instantaneous voltage value.

[0081] The calculation module 302 is further configured to: Calculating the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; According to the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage at an interval of one power frequency cycle are calculated.

[0082] The first detection module 303 is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current.

[0083] The first detection module 303 is further configured to: In response to the amplitude difference of the positive sequence current being less than zero, the amplitude difference of the negative sequence current being greater than zero, and the sum of the amplitude differences of the plurality of positive sequence currents being greater than or equal to a first threshold, it is determined that a line break fault occurs in the power system.

[0084] The second detection module 304 is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage in response to the inability to determine a line break fault through the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current.

[0085] The second detection module 304 is further configured to: In response to the amplitude difference of the zero-sequence current being greater than zero, the amplitude difference of the zero-sequence voltage being greater than zero, and the amplitude difference of the zero-sequence voltage being greater than or equal to a second threshold, it is determined that a line break fault occurs in the power system.

[0086] The second detection module 304 is configured to: In response to a line break fault occurring in the power system, a location where the line break fault occurs in the power system is determined.

[0087] The second detection module 304 is further configured to: In response to a line disconnection fault occurring in the power system, calculating a line voltage amplitude difference between any two phase nodes in the three-phase nodes; The location where the line disconnection fault occurs in the power system is determined according to the line voltage amplitude difference.

[0088] The second detection module 304 is further configured to: In response to the line voltage amplitude difference being less than or equal to a third threshold, it is determined that a location where a line break fault occurs in the power system is on a power source side of the power system.

[0089] For the convenience of description, the above device is described in terms of functions divided into various modules. Of course, when implementing the present application, the functions of each module can be implemented in the same or multiple software and / or hardware.

[0090] The device of the above embodiment is used to implement the corresponding method for detecting faults in the power system in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0091] Based on the same technical concept, corresponding to any of the above-mentioned embodiments, the present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for detecting faults in the power system as described in any of the above embodiments is implemented.

[0092] Figure 4 A schematic diagram of an exemplary electronic device according to an embodiment of the present application is shown, and the device may include: a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, the memory 1020, the input / output interface 1030, and the communication interface 1040 are connected to each other in communication within the device through the bus 1050.

[0093] The processor 1010 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0094] The memory 1020 may be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1020 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program codes are stored in the memory 1020 and are called and executed by the processor 1010.

[0095] The input / output interface 1030 is used to connect the input / output module to realize information input and output. The input / output module can be configured in the device as a component (not shown in the figure), or it can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device may include a display, a speaker, a vibrator, an indicator light, etc.

[0096] The communication interface 1040 is used to connect a communication module (not shown) to realize communication interaction between the device and other devices. The communication module can realize communication through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0097] The bus 1050 includes a path that transmits information between the various components of the device (eg, the processor 1010 , the memory 1020 , the input / output interface 1030 , and the communication interface 1040 ).

[0098] It should be noted that, although the above device only shows the processor 1010, the memory 1020, the input / output interface 1030, the communication interface 1040 and the bus 1050, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, it can be understood by those skilled in the art that the above device may also only include the components necessary for implementing the embodiments of the present specification, and does not necessarily include all the components shown in the figure.

[0099] The electronic device of the above embodiment is used to implement the corresponding method for detecting faults in the power system in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be described in detail here.

[0100] Based on the same technical concept, corresponding to any of the above-mentioned embodiment methods, the present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute the method for detecting faults in the power system as described in any of the above embodiments.

[0101] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0102] The computer instructions stored in the storage medium of the above embodiments are used to enable the computer to execute the method for detecting faults in the power system as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0103] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0104] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power / ground connections to the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device may be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present application are to be implemented (that is, these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with changes in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0105] Although the present application has been described in conjunction with specific embodiments of the present application, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the discussed embodiments.

[0106] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A method for detecting a fault in an electric power system, comprising: Obtaining instantaneous current values ​​and instantaneous voltage values ​​of three-phase nodes of a primary device in the power system; Calculate the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node of the secondary device according to the instantaneous value of the current and the instantaneous value of the voltage; Determining whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current; In response to failure to determine a line break fault through the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current, determining whether a line break fault occurs in the power system based on the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage.

2. The method of claim 1, wherein: The step of calculating the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node according to the instantaneous current value and the instantaneous voltage value further comprises: Calculating the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; According to the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage at an interval of one power frequency cycle are calculated.

3. The method of claim 1, wherein: The determining whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current further comprises: In response to the amplitude difference of the positive sequence current being less than zero, the amplitude difference of the negative sequence current being greater than zero, and the sum of the amplitude differences of the plurality of positive sequence currents being greater than or equal to a first threshold, it is determined that a line break fault occurs in the power system.

4. The method of claim 1, wherein: Determining whether a line break fault occurs in the power system according to the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage further includes: In response to the amplitude difference of the zero-sequence current being greater than zero, the amplitude difference of the zero-sequence voltage being greater than zero, and the amplitude difference of the zero-sequence voltage being greater than or equal to a second threshold, it is determined that a line break fault occurs in the power system.

5. The method of claim 1, wherein: Determining whether a line disconnection fault occurs in the power system further comprises: In response to a line break fault occurring in the power system, a location where the line break fault occurs in the power system is determined.

6. The method of claim 5, wherein: In response to a line break fault occurring in the power system, determining a location where the line break fault occurs in the power system further comprises: In response to a line disconnection fault occurring in the power system, calculating a line voltage amplitude difference between any two phase nodes in the three-phase nodes; The location where the line disconnection fault occurs in the power system is determined according to the line voltage amplitude difference.

7. The method of claim 6, wherein: Determining the location where the power system has a line break fault according to the line voltage amplitude difference further comprises: In response to the line voltage amplitude difference being less than or equal to a third threshold, it is determined that a location where a line break fault occurs in the power system is on a power source side of the power system.

8. A device for detecting a fault in an electric power system, comprising: An acquisition module is configured to acquire instantaneous current values ​​and instantaneous voltage values ​​of three-phase nodes of a primary device in the power system; A calculation module is configured to calculate the amplitude difference of the positive sequence current, the amplitude difference of the negative sequence current, the amplitude difference of the zero sequence current and the amplitude difference of the zero sequence voltage of the three-phase node of the secondary device according to the instantaneous value of the current and the instantaneous value of the voltage; A first detection module is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the positive sequence current and the amplitude difference of the negative sequence current; The second detection module is configured to determine whether a line break fault occurs in the power system based on the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage in response to the inability to determine a line break fault through the amplitude difference of the positive-sequence current and the amplitude difference of the negative-sequence current.

9. The device of claim 8, wherein: The computing module is further configured to: Calculating the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage of the three-phase node according to the instantaneous value of the current and the instantaneous value of the voltage; According to the amplitude of the positive-sequence current, the amplitude of the negative-sequence current, the amplitude of the zero-sequence current and the amplitude of the zero-sequence voltage, the amplitude difference of the positive-sequence current, the amplitude difference of the negative-sequence current, the amplitude difference of the zero-sequence current and the amplitude difference of the zero-sequence voltage at an interval of one power frequency cycle are calculated.

10. The device of claim 8, wherein: The first detection module is further configured to: In response to the amplitude difference of the positive sequence current being less than zero, the amplitude difference of the negative sequence current being greater than zero, and the sum of the amplitude differences of the plurality of positive sequence currents being greater than or equal to a first threshold, it is determined that a line break fault occurs in the power system.

11. The device of claim 8, wherein: The second detection module is further configured to: In response to the amplitude difference of the zero-sequence current being greater than zero, the amplitude difference of the zero-sequence voltage being greater than zero, and the amplitude difference of the zero-sequence voltage being greater than or equal to a second threshold, it is determined that a line break fault occurs in the power system.

12. The device of claim 8, wherein: The second detection module is further configured to: In response to a line break fault occurring in the power system, a location where the line break fault occurs in the power system is determined.

13. The device of claim 12, wherein: The second detection module is further configured to: In response to a line disconnection fault occurring in the power system, calculating a line voltage amplitude difference between any two phase nodes in the three-phase nodes; The location where the line disconnection fault occurs in the power system is determined according to the line voltage amplitude difference.

14. The device of claim 13, wherein: The second detection module is further configured to: In response to the line voltage amplitude difference being less than or equal to a third threshold, it is determined that a location where a line break fault occurs in the power system is on a power source side of the power system.

15. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

16. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 7.

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